Method of making ether and ester derivatives of polysaccharides synthesized through bacterial action



Patented June 11, 1940 METHOD OF MAKING ETHER ESTER DERIVATIVES OF POLYSAOCHABIDES :{ggHESTZED THROUGH BACTERIAL AC- No Drawing. amine-anon July 29, v11m, Serial No. 156,426

.13 Claims. (Cl. i95-l2) This invention relates to the production of polysaccharide materials by the action oi various micro-organisms on suitable culture media, and

v to processes for converting these polysaccharides into their ether, mixed ether, ester, mixed ester or mixed ether-ester derivatives. i

It is the object of this invention to produce polysaccharlde materialsby the action of various micro-organisms on suitable culture media and l0 in particular to produce dextran; and to thereafter subject the polysaccharide materials such as dextran to a process of etherification or esterification either while the materials are in the culture media or after separation therefrom so as to produce the new products of resinous character such as the benzyl ether of dextran, the butyl ether of dextran, etc.

The polysaccharides are produced by inoculating, media containing sucrose, nitrogenous com-; pounds and various salts withbacteria of known genus and species. These bacteria may be placed in one of two groupings, those that produce polysaccharides knownas levans, or those that produce the polysaccharides known as dextrans.

2B The two types of polysaccharidesare distinguished from one another by the fact that on hydrolysis with acids or enzymes, the dextrans Iyieldonlydextrose while the levans yield only levulose. As specific examples, Bacillus mesen- 80 teflcus, B. v substilis, B. megatherium, Pseudo,-

moncs pruni, Ps. primicola or F8. phas eoli may be employed for the production of the levan type of polysaccharide, while Leuconostoc mesonteroides or L. dextrcnicum may be used for the as production of the dextran type.

p The culture media employed must contain some sucrose; can be either refined or crude sucrose, molasses or any similar sucrose containing material. Nitrogen may beadded inthe miorm of commercial peptone, beef extract for,

other nitrogen containing material. If molasses is used as the sucrose source, nitrogenous compounds lnsumcient quantity are present in it so] dipotassium phosphate 0.2% and sodium chloride.

0.1%. The pH of the medium preferably is ad- 50 justed to slightly on the alkaline side of neutrality.

The production ofuthe polysaccharide. is favored by reaction of the media alightly alkaline throughout the period of fer-i ,u' mentation. be accomplished by the periodic addition of alkali to the fermenting media or by using an excess of calcium carbonate in the media. After inoculation the cultures are incubated at the temperature most favorable to the growth of the micro-organism being used. .For one of the preferred forms, Leuconostoc mesenteroides, this temperature is around degrees C. The progress of the fermentation may be followed by periodically removing samples of the fermenting culture media and precipitating the polysaccharide contained in them by the addition of three to five times their volume of alcohol. The precipitated polysaccharide may then be weighed. When a maximum of polysaccharide has been formed the culture media are ready for the etherification or esterification processes. The length of time necessary for the maximum of polysaccharide to be formed will vary with the organism employed, the temperature of incubation, the concentration of sucrose and other factors.

The polysaccharide may be isolated from the solution by precipitation with alcohol or acetone. Preferably the reaction of the fermented medium is first adjusted to the neutral point to lessen the possibility of hydrolysis of the polysaccharide, and the solution then concentrated under reduced pressure at a temperature of 40 to 50 degrees C. to approximately one-fourth its original volume. The solution is then-poured,

with stirring, into three to five times its volume of alcohol or acetone. The polysaccharide may ture media by the addition of alcohol or acetone,

but it is then necessary to use a considerably larger amount of the precipitating agent.

1hr the preparation of the ether and ester derivatives of these polysaccharides it is not necessary that they first beisolat'ed from the culture media in which they were formed. Instead the necessary reagents may be added directly to the fermehted' media, and after completion of the reaction,' the'ether. ester, or mixed. ether ester derivatives can be recovered from the mixture, either by a'simplemechanical process in case the product is 'water insoluble, or by the use of specific precipitating agents.

If, however, the polysaccharide is not removed from ,the culture solution! before esterification or etherification, the product obtained'is a mixture of compounds. It will contain, besides the ethers and/or esters of thejpolysaccharide, the

corresponding'fderlvatives of any excess sucrose or metabolic products remaining in' the fermented culture media. In some cases this may be desirable since a blending 01 these various derivatives yields a product with a range oi solubilities. However, in cases in which a product with the specific properties of the polysaccharide derivative alone are desired, it is necessary either to separate the dextrans or levans from the culture media before chemical treatment, or else to remove the undesirable lay-products, from the mixture obtained by the direct treatment of the fermented media, by the use of specific solvents.

Whether the fermented media are treated directly, or the polysaccharides first isolated by alcohol or acetone precipitation, the proportions oi the reactants used in the preparation oi the ether derivatives are approximatelyras follows: one mol of the polysaccharide. 3.5 mols oi the alkyl or aralkyl halide and-4.5 mols of sodium hydroxide. If the polysaccharide was isolated irom the medium before the chemical treatment, sui'iicient water must be added to the mixture so as to yield approximately a 10 per rent solution of the sodium hydroxide.

11' the fermented culture medium itself is used,

the amount of water present should be so regulated by concentration or dilution to again yield approximately a 10 per cent solution of the alkali. After addition of the reagents the mixture is heated for a predetermined time, usually 4 to 6 hours, at a temperature anywhere from to 130 degrees C. This temperature depends on the derivative being prepared.

In general, the higher the temperaturev and the longer the period of heating the greater will be the number of hydroxyl groups in the polysaccharide which will be substituted by the organic radical of the halide compound used. The temperature and time of heating employed is consequently governed by the type of product desired. The organic halide used may be any member of the aliphatic series such as methyl chloride, ethyl chloride, propyl or isopropyl chloride, butyl chloride or any oil its isomers, etc., or any one of the araliphatic series such as benzyl chloride.

The aliphatic derivatives are water soluble, at least as high as the butyl derivative. The benzyl ethers are generally water insoluble. Regardless of the type oi organic halide used, increasing the proportion oi halide to polysaccharide, running the reaction at a higher temperature and for a longer period of time wiilgenerally result in a decreased water solubility for the products obtained.

' It is to be understood that the organic halide used may 'be either the chloride. bromide or iodide derivative. For purposes of economy, the chlorides are generally employed.

At the conclusion of the reaction period excess halide is recovered by any suitable process such as steam distillation. The product is isolated by mechanical meansif it is water insoluble or by precipitation if it is water soluble.

The process may be varied by the simultaneous introduction of two or more organic halide compounds into the reaction mixture, in which case the product will be a mixed ether; or a particular ether derivative may be prepared and the prodnot from the reaction then treated with a difl'erent organic halide to yield a mixed ether derivative. Again, an ether derivative may be prepared and then further treated with organic acid chlorides, acid anhydrides and the like for the preparation oi mixed ether-ester derivatives. Such variations in treatment are, of course, almost without number.

The products in general are to be described as plastic, amorphous masses, either water soluble or insoluble depending upon the reaction conditions and the particular halide employed. As an example, the benzyl ether of dextran is a water insoluble material which resists the action of the common organic solvents, while the butyl ether of dextran is water soluble.

The following are examples of specific practices 01' our method for the production oi new products. It will be understood we do not desire to be confined to the detailed proportions, temperatures and pressures, although we are reciting hereinafter those that we have found to 3e the preferred temperatures and other condions.

It will be further understood that it is comprehended within this process the production of j a-large number 01 allied materials.

we comprehend other similar new materials.

EXAIIPLI I "Benzyl ether derivatives This process may be carried out directly on the fermented culture media containing the polysaccharide, suchas dextran. although the same process can be' employed with the extracted dex-' tran after it has-been removed irom the culture media. This statement applies to'the other examples hereinafter recited.

To a portion of the fermented'culture medium in which the polysaccharide has been produced and in which there is approximately 30 gm. of the polysaccharide, is added gm. of benzyl chloride and 40 gm. oi sodium hydroxide. The resulting mixture is heated for approximately five hours. If the temperature is held at 80 to 85 degrees 6., the crude product is light orange in color and soft and rubbery in consistency. When higher temperatures of from to degrees C. are employed. an orange-brownprodnot is obtained of the same consistency but of greater resistance to solvents. The time oi heating may range from 4 to 6 hours but 5 hours is the preferable time. By varying thetemperature of this benzylation process, to solubilitiesin various solvents of the resulting products are varied. These products are substantially in soluble in water. b I

- 1 ExAurnnII Butul ether derivatives it:

To a portion of the fermentedculture medium containing 30 gm. of dextran, we add 120..gm.; oi butyl chlorideand 40 gm. of sodium hydroxide. The mixture is heated at 100 degrees vQ. fori'our hours. The derivative is anamorphous mass that is water soluble.

y Elam n1 Mired benzyl ether-butyl ether derivatives alcohol by steam distillation, the resulting product is isolated as a rather firm and j leathery amorphous mass.

70 to 85 degrees C. for a period of live hours. -j 'A'iter removal of excess benzyl chloride and benzyl tranicum and acetyintin: directiii'lthe 'visco culture medium containing theidextran;

13. In a method of producing gcetyl esters of dextran, mixing a sucrose culture medium in which dextran has been eyntheslzed by bacterialogical action' -bompri'sing inoculating: culture medium containing sucrose with bacterium eeiected from the zroup consisting of Leueonoatoc mesenteroides and Leueonoltoc mam with sodium hydroxide 'and acetyl chloride, and nesting the'mixture until a rubbery mess of via- 'cous material separates therefrom.

Y GRANT L. SI'AHLY.

WARNER. 'W. CARLSON. 

